van der Waals Interactions and Hadron Resonance Gas: Role of resonance widths modeling on conserved charges fluctuations

TL;DR

This study explores how van der Waals interactions and resonance width modeling affect conserved charge fluctuations in the hadron resonance gas, revealing that these factors significantly influence the model's agreement with lattice QCD data.

Contribution

It introduces a quantum van der Waals extension to the hadron resonance gas model and examines the impact of resonance widths and additional baryons on charge fluctuation observables.

Findings

QvdW interactions qualitatively change susceptibility behavior.

Finite resonance widths improve some observables but worsen others.

Adding unconfirmed baryons improves overall model agreement.

Abstract

The quantum van der Waals (QvdW) extension of the ideal hadron resonance gas (HRG) model which includes the attractive and repulsive interactions between baryons -- the QvdW-HRG model -- is applied to study the behavior of the baryon number related susceptibilities in the crossover temperature region. Inclusion of the QvdW interactions leads to a qualitatively different behavior of susceptibilities, in many cases resembling lattice QCD simulations. It is shown that for some observables, in particular for $\chi_{11}^{BQ} / \chi_2^B$, effects of the QvdW interactions essentially cancel out. It is found that the inclusion of the finite resonance widths leads to an improved description of $\chi_2^B$, but it also leads to a worse description of $\chi_{11}^{BQ} / \chi_2^B$, as compared to the lattice data. On the other hand, inclusion of the extra, unconfirmed baryons into the hadron list leads to a simultaneous improvement in the description of both observables.